The present invention relates to a device for the manufacture of a spun yarn or thread from a staple sliver.
Devices are known in the textile art that are used for air spinning processes. Such a device is disclosed, for example, by Specification EP 854 214 (equivalent to U.S. Pat. No. 5,927,062), which is shown in FIG. 1. It can be seen how a sliver 1 is delivered from a pair of delivery rollers 2 (in most cases a drafting device) and runs through a fiber guide element 3.1. The fiber guide element 3.1 exhibits a fiber conveying channel 4 with a helically-shaped fiber guide surface 5, whereby this ends at a fiber delivery edge 6. Arranged at a certain distance from the fiber guide element 3.1, and from the fiber delivery edge 6 respectively, is a spindle 7 with a yarn guide channel 8 and an inlet aperture mouth 9 allocated to the yarn guide channel 8. Between the fiber guide element 3.1 and the inlet aperture mouth 9 is a fluid device for generating an eddy current around the inlet aperture mouth 9 (fluid device not shown). The fluid device generates an eddy current 11 around the inlet aperture mouth 9, and around the spindle 7, respectively, in the area 14. FIG. 1 shows the air spinning device in diagrammatic form only. The space 14 is normally enclosed by a housing and can therefore be designated as an eddy chamber (14.1, see following Figures). As a fluid, compressed air is usually used. Due to the eddy current 11 which is created, the free fiber ends 12 of the sliver 1 lie around the inlet aperture mouth 9. As a result of the movement of the sliver 1 in the direction of the arrow, a relative rotating movement of the free fiber ends 12 is created around the inlet aperture mouth 9, and, as a result, around the sliver 1. From the sliver 1, a spun yarn 10 is accordingly derived.
The present invention is concerned with the guidance of the fluid (air) flowing out of the fluid device. It is concerned in particular with the area of the eddy chamber 14.1 in the immediate vicinity of the outlet apertures for the fluid.
A further instance of the prior art, according to Japanese Specification JP 3-10 63 68, is shown in FIGS. 2 and 2a. In FIG. 2, essentially the same components are shown as in FIG. 1 (with one change, see FIG. 2a). In particular, the pair of delivery rollers 2 and the spindle 7 with the yarn guide channel 8 can be identified. By analogy with FIG. 1, a fluid device creates an eddy current here also. In this situation, the fluid device consists of several jet nozzles 13.1. The jet nozzles consist as a rule of cylindrical holes, or apertures, from which the fluid (air is preferred) is introduced under pressure into the eddy chamber 14.1. The eddy chamber 14.1 has a circular cross-section. As a result of the direction of flow created by the arrangement of the holes and due to the circular cross-section of the eddy chamber 14.1, the compressed air flowing in creates an eddy flow around the inlet aperture mouth 9 of the spindle 7. As can be seen from FIG. 2, the fiber guide element 3.1 includes a casing jacket 3a, which also forms the fiber conveying channel 4. Connected directly to this Figure, the fluid device (represented by the holes or jet nozzles 13.1) is integrated into the casing jacket of the fiber guide element 3a. In the device shown, the eddy chamber housing 15 and the casing jacket of the fiber guide element 3a are two separate components. It is, however, entirely possible, and known from the prior art, for both components to be designed also as one element (as a single piece). Whether these elements are designed as single pieces or as separate components is not of significance to the present application.
In FIG. 2a, the fiber guide elements 3.1 of FIG. 2 is shown in a three-dimensional view. By contract with FIG. 1, the fiber guide elements 3.1 in FIG. 2 does not exhibit a helical but rather a flat fiber guide surface 5.1. A further difference between this and FIG. 1 les in the absence of a fiber delivery edge. Instead of the fiber delivery edge, the fiber guide elements part 3b exhibits a truncated cone shape. The purpose of this cone 3b is to produce what is referred to as a false yarn core.
The intention of this is to prevent a false twist (incorrect rotation of the sliver) from the inlet aperture mouth 9 extending backwards through the fiber guide element 3.1 as far as against the clamping gap of the par of delivery rollers 2 (referred to as twist stop). A false twist prevents a correct twist or rotation of the free fiber ends about the (untwisted) yarn core. In the event of a false twist, the core of the sliver rotates with the free fiber ends and prevents the spinning of the fibers. With the prior art according to FIG. 1, the twist stop is achieved by the helical shaped fiber guide surface 5, which is intended to render impossible the rotation of the sliver 1 towards the delivery rollers 2.
Another instance of prior art which relates to the device according to the invention is to be found in a patent application from Applicants still unpublished at the time of this application (International Application Number: PCT-CH-01-00569).